Critical dynamics in frustrated systems and spin liquids

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One of the major goals of condensed matter physics is to discover new materials with novel, and potentially useful, properties. But since this must be achieved using the same basic constituents - protons, neutrons, electrons - as "ordinary" matter, the novelty must come from how they are combined, and the ways in which the parts interact with each other to give a different whole. Even when their constituents are simple, systems with many strongly interacting parts are difficult to understand theoretically. Progress in condensed matter physics therefore relies on the development of new theoretical strategies for understanding the emergence of large-scale behaviour in complex systems.A promising place to look for materials with novel properties is in "frustrated magnets", systems that are prevented, or at least hindered, from forming the usual magnetic states with which we are familiar. In physics, frustration refers to the presence of competing interactions that cannot simultaneously be satisfied, and occurs in certain materials containing localised magnetic moments, or "spins". A particularly novel form of matter that occurs in frustrated magnets is the so-called spin liquid, where the magnetic moments are strongly correlated but do not settle into an ordered configuration, analogous to the dense but disordered arrangement of molecules in an ordinary liquid such as water. Examples include the "spin ice" materials, which have a number of unusual magnetic properties, including hosting particles that behave as magnetic monopoles. Much experimental and theoretical work is currently under way to understand the properties of these materials, as well as to predict and discover new phenomena that they may exhibit.This research project will develop a new theoretical approach to explore the dynamics of frustrated systems, including frustrated magnets such as spin ice. The strategy will be to exploit the peculiar properties of systems near phase transitions, sudden and dramatic differences in behaviour that occur as temperature (or another physical parameter) changes, such as the transition from liquid water to steam. By developing and applying new theoretical and computational techniques, this fundamental research will pave the way for future technological applications of frustrated materials.